The Approach to Dental Caries Prevention in a Case of Agenesis of the Major Salivary Glands: A Case Report

Xerostomia leads to great challenges for patients and dentists in managing and maintaining oral health due to the high risk of developing dental caries. We discuss a case of a 10-year-old male patient who presented with complaints of decayed teeth and difficulty chewing and swallowing food. He had bilateral congenital stenosis and stricture of lacrimal ducts and a family history of lacrimal gland agenesis and Hashimoto’s disease. The diagnosis reached was agenesis of all major salivary glands confirmed by saliva testing and ultrasound examination of the glands. Comprehensive preventative, restorative, and maintenance protocols based on caries management by risk assessment (CAMBRA) were implemented, including fissure sealants, amalgam and composite resin restorations, professional and home-applied fluoride, chlorhexidine mouthwash, frequent water consumption, and two-monthly recalls. We were able to stabilize the patient’s risk of dental caries for over three years. The implementation of stringent restorative, preventive, and maintenance protocols is key to improving and maintaining oral health in severe cases of xerostomia.


Introduction
Xerostomia is defined as dryness of the mouth due to decreased secretion of saliva.The prevalence of xerostomia in population-based samples was estimated in a systematic review to range between 0.9% and 64% [1].The systematic review gave results on individuals older than 18 years of age.Many other studies have documented that the prevalence of xerostomia increases with age, certain medications, and other underlying diseases e.g Sjogren's syndrome [2].However prevalence studies of xerostomia among children were confined to those undergoing cancer treatment or any form of radiation-based therapy or those diagnosed with diseases that impair salivary glands' function [3].The causes of xerostomia can be classified into salivary and non-salivary causes [4].Non-salivary causes include dehydration, cognitive alteration, neurological or oral sensory dysfunction, psychological, and mouth breathing due to obstruction in the upper airway tract.On the other hand, salivary causes include diseases such as autoimmune disorders (e.g.Sjogran's syndrome, systemic lupus, sarcoidosis, rheumatoid arthritis, scleroderma, primary biliary cirrhosis), diabetes mellites, HIV, herpes virus family, hepatitis C, and end-stage renal disease.Other salivary causes include congenital, hereditary, treatment side effect, salivary gland trauma or tumor, and nutritional deficiencies/ eating disorders.This case was diagnosed under the category of congenital causes which may include either hypoplasia or aplasia of salivary glands.Aplasia of salivary glands is a rare condition and is usually associated with either hypoplasia or aplasia of lacrimal glands [5][6][7].These patients can experience multiple side effects including increased risk of dental caries, oral candidiasis, ascending sialadenitis, laryngitis, pharyngitis, and difficulty in swallowing [8].

Case Presentation
This was a 10-year-old male who was referred from a local dentist for assessment and management of dry mouth and multiple carious teeth.Past medical history revealed bilateral congenital stenosis and stricture of lacrimal gland ducts in addition to agenesis of superior lacrimal canaliculi.The patient suffered from dry eyes, seasonal asthma, and bilateral mild fixed flexion knee deformities.Ongoing medications included hydrating eye drops and occasional use of Ventolin.
Family history showed multiple family members from the father side who suffered from agenesis of lacrimal glands, suggesting a possibility of a genetic component.On the patient's mother side, his great grandmother was diagnosed with Hashimoto's disease.His mother had multiple symptoms suggestive of autoimmune conditions including Hashimoto's disease, rash, photosensitivity, arthritis with a possible unifying diagnosis of systemic lupus erythematosus.
Past dental history included receiving regular dental care visits at a local dentist since the age of 5 years.During this period, the patient had multiple glass ionomer restorations, pulpotomy treatments, and extraction for multiple carious primary teeth.His first permanent molars became carious soon after eruption and were treated by resin-based fissure sealant.He also received multiple oral hygiene instructions, diet counselling, and professionally applied topical fluoride at the local dentist.He was first noticed with dry mouth two years before his referral to the pediatric dentistry consultant.Since the patient's referral, he was following regular oral hygiene practices of brushing with fluoridated toothpaste twice a day.His diet content and frequency of snacking did not seem to be cariogenic, with adequate breaks between meals and snacks.
Extra and intra oral examinations were performed and the patient's oral hygiene was rated fair with absence of gingival inflammation and dental plaque.However, there was a reduction of the patient's saliva production evident by overall dryness of the oral mucosa and slow saliva secretions after drying the lower lip.The patient was in his late mixed dentition stage of dental development with class I molar relationship.He had partially erupted teeth (#14 and #24) and deep palatal fissures on teeth (#12 and #22).He also had multiple carious primary teeth with remaining roots and demineralization on the mesial surface of tooth #36 and cervical surfaces of most of his permanent teeth.Cavitated clinical caries was evident on mesial and distal surfaces of tooth #31 and mesial surface of tooth #41.Existing restorations included defective resinbased fissure sealants on first permanent molars and large occlusal composite resin restoration on tooth #85 (figure 1)  Saliva testing was performed multiple times using GC saliva-check buffer-kit to determine different aspects of quantity and quality of saliva.Resting saliva was examined through visual inspection of the level of hydration that was low indicating a low resting flow of saliva.Saliva consistency was frothy and bubbly indicating an increased viscosity of saliva.The quantity of five minutes stimulated saliva was <3.5 ml indicating a very low stimulated saliva flow.The buffering capacity of saliva was found to be very low (scores between 0-5 points as compared to a normal score of 10-12) and saliva pH measurement was 6.2 indicating moderately acidic saliva.Special imaging for salivary glands were performed including ultrasonography that revealed bilateral absence of all major salivary glands (parotid and submandibular) (figure 3).Medical consultation with rheumatology did not suggest any evidence of autoimmune disease.However, the patient was planned for regular reviews for possible late presentation of an autoimmune disease.The patient was also referred to medical genetics to investigate the possibility of a hereditary cause of xerostomia e.g.aplasia of the lacrimal and major salivary glands (ALSG) and the results came back negative for any genetic component related to his condition.
Based on previous clinical and imaging findings, the patient was diagnosed with complete bilateral agenesis of all major salivary glands (parotid, submandibular, and sublingual) as evident on ultrasonography.A comprehensive treatment plan was created and involved prevention, restorations/ remineralization, and regular follow ups.Caries management by risk assessment (CAMBRA) protocol was used throughout patient's dental management plan [9].Prevention measures focused on improving brushing skills to remove dental plaque twice a day, using high fluoride concentration toothpaste (5000 ppm), maintaining low bacterial counts by using 0. 2% chlorhexidine mouthwash (used once a day for a period of one week and repeated every month) and sipping water frequently to keep the mouth hydrated and using saliva stimulants e.g.sugar-free gum.Fissure sealants was placed on palatal fissures of teeth #12, #22, and on any newly erupting teeth.Restorative treatments started by extracting carious primary teeth and remaining roots.This was followed by placing amalgam restorations on permanent molars and composite resin restorations on anterior teeth.Remineralization of non-cavitated carious lesions was achieved by daily home application of high fluoride toothpaste in special trays to be applied one hour before bedtime, and by monthly application of fluoride varnish on all teeth.At the end of the remineralization therapy, the patient was placed on regular follow ups and maintenance plan every three months that involved caries monitoring and reinforcing home and professional preventive care.This follow up period continued for three consecutive years during which no new carious lesions were developed, and oral hygiene was stabilized (Figures 6 and 7).

Discussion
The diagnosis of the xerostomia depends on accurate history taking, physical examination, testing of saliva quantity and quality, medical consultation to rule out underlying autoimmune diseases, salivary gland imaging, and at last biopsy.This case was considered among the rare cases as shown earlier in the introduction section.The steps taken to diagnose the condition went from simple observation of the presence of saliva in the mouth, followed by saliva testing, to more advanced investigation e.g.ultrasonography, nuclear med scan and referral to medical genetics.This gradual and logical mean of investigation help reduce patient discomfort and cost, and at the same time reduce the use of more advanced and expensive hospital resources.
The comprehensive dental treatment and management plan using sound scientific evidence was crucial in the success of maintaining a good oral health for this compromised patient.Following the CAMBRA protocol had a great impact on the overall success of this case over a period of three years.Amalgam restorations are becoming less frequently used nowadays due to patient preferences and improvements made to composite resin materials and indirect restorative options e.g.porcelain inlays/ onlays.However, as compared to composite resin restorations, the properties, longevity, success rates and lower cost of amalgam restorations make them a superior choice in such cases of extreme xerostomia [10,11].
The choice of using mostly composite resin restorations instead of glass ionomer restorations in restoring the interproximal lesions of the mandibular anterior teeth can be argued.Although the patient may benefit from the fluoride-releasing characteristic of glass ionomer restorations, the preventive regimen that we adopted included frequent application of high concentration fluoride agents was deemed superior to the minimal fluoride release from the glass ionomer restorations; thus, justifying the use of composite resins.
In this case, the preventative regimen focused on restoring the imbalance caused by the lack of salivary secretion that placed the patient in the extreme risk category for developing dental caries.The preventive regimen included cariostatic agents (0.2% chlorhexidine mouthwash), remineralizing agents (high fluoride concentration toothpaste and professional application of fluoride varnish), diet counseling with oral hygiene instructions, use of saliva stimulants, and frequent dental visits.
The patient and his parents were highly motivated about the preventive and remineralization therapies.After three years of follow up the patient did not develop new carious lesions.The size of the mesial lesion on tooth #32 remained the same and there was evidence of remineralization of the other demineralizing lesions (mesial surfaces of teeth #36 and #46).The fillings were all intact except for marginal staining around the margins of the composite restoration of tooth #31 that was replaced by composite resin strip crown.
Reinforcing oral hygiene, home care, and the family willingness to follow dentist instructions and advice had a remarkable effect on the overall success of this case.It is also worth mentioning that considering the social behavioral background of the patient in the formulation of the treatment plan, choice of restorative materials, and simplification of oral home care, played a huge role in patient compliance throughout the treatment and maintenance journey for this child.

Conclusions
Following and well-structured and evidence-based dental management of patients suffering from severe xerostomia is essential to maintain good oral health.Such cases of agenesis of all major salivary glands are rare however, it takes great effort from the dentist and the patient/ patient's family to prevent dental caries for those high-risk patients.Existing evidence-based protocols such as CAMBRA was found to be successful in maintain oral health and preventing dental diseases in such cases.After all, dentists should be skilled in finding the cause of dental caries for their patients and not relay on traditional oral hygiene instructions without investigating for the root cause of the illness.

FIGURE 1 :
FIGURE 1: Intra-oral clinical photos before treatment a) Intra-oral clinical photo frontal view b) Intra-oral clinical photo of maxillary arch c) Intra-oral clinical photo of mandibular arch -Red arrows: demineralized enamel lesions and cavitated dental caries -Black arrows: remaining roots -Blue arrows: deep palatal pits

FIGURE 2 :
FIGURE 2: OPG and bitewing radiographs before treatment a) OPG radiograph b) Right side bitewing radiograph c) Left side bitewing radiograph -Yellow arrows: recurrent dental caries under existing restorations/ fissure sealants

FIGURE 3 :
FIGURE 3: Ultrasonography of normal and missing right and left parotid and submandibular salivary glands a) Ultrasonography of normal parotid gland b) Ultrasonography of missing right parotid gland c) Ultrasonography of missing left parotid gland d) Ultrasonography of normal submandibular gland e) Ultrasonography of missing right submandibular gland f) Ultrasonography of missing left submandibular gland -White arrows: location of salivary glands with distinction between normal images (a and d) and images with missing salivary glands (b,c,e,f)

FIGURE 4 :
FIGURE 4: Nuclear medicine scan of major salivary glands showing no uptake by major salivary glands a) Anterior view showing no uptake by major salivary glands b) Left view showing no uptake by major salivary glands c) Right view showing no uptake by major salivary glands -Red arrows: position of parotid salivary glands -Blue arrows: position of submandibular salivary glands

FIGURE 5 :
FIGURE 5: Major salivary glands function (secretion and uptake) graph a) Salivary gland function graph of parotid gland b) Salivary gland function graph of submandibular gland c) Salivary gland function graph of the whole mouth

FIGURE 6 :
FIGURE 6: Intra-oral clinical photos after treatment a) Intra-oral clinical photo frontal view b) Intra-oral clinical photo of maxillary arch c) Intra-oral clinical photo of mandibular arch -Black arrows: amalgam restorations -Blue arrows: sealants on palatal fissures -Red arrows: non-cavitated demineralized enamel lesions